Lucifer's Hammer by Larry Niven is a fantastic book that might be near what you are looking for. It's about an asteroid impact on Earth, this removes a lot of the population and infrastructure and the story focuses on a few different groups of people as they make do with what they can find or scavenge, and then the resource battling that goes on between groups.

A story line I remember well is on a group that found an abandoned neighborhood and were astonished to find that it still had running water from the nearby local dam/reservoir. They lived here for quite a while in their relative luxury until it just stopped working one day. A burst pipe in some other neighborhood had slowly drained the dam faster than they would have used it up.

Anyway, it's a great book because it feels so realistic as to what would really happen and the struggles people would actually be going through.